Input/output device information management system for multi-computer system

ABSTRACT

In a multi-computer system having a plurality of computers, an input/output device configuration definition table and an input/output device configuration reference table are adapted to be collectively managed. A configuration management program manages the configuration definition of all input/output devices of a plurality of computers by using the input/output device configuration definition table, and generates a changed data file when an input/output device configuration is changed. Dynamic system alteration is effected by changing the contents of the input/output device configuration reference table stored in a shared memory, in accordance with the changed data file. The input/output device configuration definition table and the input/output device configuration reference table each have an input/output device information part and an input/output device connection information part arranged in a matrix form to allow addition/deletion of an input/output device and a computer.

The present application is a continuation of application Ser. No.10/337,321, filed Jan. 7, 2003; which is a continuation of applicationSer. No. 09/963,473, filed Sep. 27, 2001, now U.S. Pat. No. 6,526,441;which is a continuation of application Ser. No. 09/638,027, filed Aug.15, 2000, now U.S. Pat. No. 6,341,308; which is a continuation ofapplication Ser. No. 08/948,071, filed Oct. 9, 1997, now U.S. Pat. No.6,115,738; which is a continuation of application Ser. No. 08/371,376,filed Jan. 11, 1995, now U.S. Pat. No. 5,717,950, the contents of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a collective management system forinput/output device information in a multi-computer system of containinga plurality of computers. More particularly, the invention relates to acollective management system for input/output (I/O) device informationin which an input/output device configuration table and an input/outputdevice configuration reference table can be updated collectively and atthe same time, the former table defining the configurations of allinput/output devices used in the multi-computer system and the lattertable having the format allowing the reference by each computer for theexecution of data input/output of each input/output unit.

DESCRIPTION OF THE RELATED ART

A conventional technique for managing of input/output device informationis disclosed, for example, in JP-A-4-90024. According to this technique,a specific computer in a multi-computer system performs systemgeneration to generate volumes resident at each computer.

Another conventional technique is disclosed in JP-A-3-269754. Accordingto this technique, identification information of input/output devicesfor each computer is stored in advance in a shared file in the form ofdatabase, and a file of input/output device configuration information,which is a combination of connection information and identificationinformation of input/output devices, is formed for each computer.

A conventional technique for dynamic system alteration is disclosed, forexample, in JP-A-3-175532. According to this technique, systemgeneration information, having a format allowing the reference by eachcomputer for the execution of data input/output of each, input/outputdevice, is stored in a memory of each computer. After the systemgeneration information is altered by a definition program at onecomputer, other computers read the altered system generationinformation.

With the conventional technique for managing of input/output devices, aninput/output configuration definition table and an input/outputconfiguration reference table are provided for each computer. It isnecessary for each computer of a multi-computer system to define theconfigurations of shared input/output devices, thereby posing a problemof lowering a resource usage efficiency and increasing the process loadof each computer caused by the need of defining the configurations.

With the conventional technique for dynamic system alteration, after aninput/output device configuration reference table stored in eachcomputer of a multi-computer system is altered, other computers arerequired to read the altered input/output device configuration referencetable, thereby posing a problem of a need of a number of processes forthe addition, deletion, or change of shared input/output devices.

SUMMARY OF THE INVENTION

It is an object of the present invention to solve the problemsassociated with conventional techniques by providing an input/outputdevice, information management system for a multi-computer system havinga plurality of computers, the management system being capable ofcollectively managing an input/output device configuration definitiontable and an input/output device configuration reference table, theformer table defining the configurations of all input/output devicesused by the multi-computer system and the latter table having a formatallowing the reference by each computer for the execution of datainput/output of each input/output device, and being capable ofdynamically updating both tables when any alteration such as addition,deletion, and change of an input/output device or a computer is made bya computer during its operation.

The above object of the invention is achieved by an input/output deviceconfiguration definition table stored in a shared file of themulti-computer system for defining the configurations of allinput/output devices used by a multi-computer system, the input/outputdevice configuration definition table having an input/output deviceinformation part and an input/output device connection information partdisposed in a matrix form. This table allows the configurations of allinput/output devices shared in the multi-computer system to be simplydefined.

The above object of the invention is achieved by an input/outputconfiguration reference table stored in a shared memory of the computernetwork, the input/output configuration reference table being obtainedby reading the input/output configuration definition table andtransforming the definition table into the format allowing the referenceby each computer for the execution of data input/output of eachinput/output device, and the 10 input/output device configurationreference table having an input/output device information part and aninput/output device connection information part disposed in a matrixform. This table allows all input/output devices shared by themulti-computer system to be managed collectively.

In the multi-computer system having a plurality of computers, theinput/output device configuration definition table and the input/outputdevice configuration reference table each have an input/output deviceinformation part storing identification information of each input/outputdevice such as a type and an attribute, and an input/output deviceconnection information part storing connection information between'input/output devices and computers, both the parts being disposed in amatrix form. With the input/output device configuration definition tableand the input/output device configuration reference table, acorrespondence between all input/output devices and computers of themulti-computer system can be managed collectively.

Any computer can collectively update both the input/output deviceconfiguration definition and reference tables by a single set ofoperations, when an input/output device or a computer is added, deleted,or changed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram showing the configuration of a multi-computersystem, and FIG. 1B is a block diagram showing the structures of aninput/output device configuration definition table and an input/outputdevice configuration reference table;

FIG. 2 is a diagram showing an example of the structure of aconfiguration management program according to an embodiment of theinvention;

FIG. 3 is a diagram showing an example of the structure of a systemgeneration procedure;

FIG. 4 is a diagram showing an example of the structure of a systemalteration procedure;

FIG. 5 is a flow chart explaining the operation of the system generationprocedure;

FIG. 6 is a flow chart explaining the operation of the system alterationprocedure;

FIG. 7 is a diagram explaining a dynamic system alteration for amulti-computer system;

FIG. 8 is a flow chart explaining the operation of an input/outputdevice information part generating process of the system generationprocedure;

FIG. 9 is a flow chart explaining the operation of an input/outputdevice information connection part generating process;

FIG. 10 is a flow chart explaining the operation of an input/outputdevice configuration definition table diagnosing process;

FIG. 11 is a flow chart explaining the operation of a changed data filegenerating process;

FIG. 12 is a flow chart explaining the operation of an input/outputdevice definition table copying process;

FIG. 13 is a flow chart explaining the operation of an associativeinput/output device identifying process of the system alterationprocedure;

FIG. 14 is a flow chart explaining the operation of a dynamic systemalteration start notifying process;

FIG. 15 is a flow chart explaining the operation of an input/outputdevice use permission setting process;

FIG. 16 is a flow chart explaining the operation of an input/outputdevice information part changing process;

FIG. 17 is a flow chart explaining the operation of an input/outputdevice information connection part changing process; and

FIG. 18 is a flow chart explaining the operation of a dynamic systemalteration end notifying process.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of an input/output device information management system ofthe invention is described in detail below with references to theaccompanying drawings.

Referring to FIGS. 1A and 1B, the input/output device informationmanagement system for a multi-computer system includes computers 1, aconfiguration management program 2, a shared file 3, a shared memory 4,an input/output device configuration definition table 5, a configurationdefinition working table 5 a, a changed data file 6, an input/outputdevice configuration reference table 7, an input/output deviceidentification information part 9, and an input/output device connectioninformation part 10.

As shown in FIG. 1A, the multi-computer system of the invention includesa plurality of computers 1, the configuration management program 2running on each computer 1 for managing the configurations of allinput/output devices, the shared file 3 for the plurality of computers1, the shared memory 4 for the plurality of computers 1, theinput/output configuration definition table 5 stored in the shared file3 for storing the data defining the configurations of all input/outputdevices used by the plurality of computers 1, the configurationdefinition working table 5 a used for editing the input/outputconfiguration definition table 5, the changed data file 6 for storingthe changed data of the input/output configuration definition table 5 a,and the input/output configuration reference table 7 stored in theshared memory 4, the input/output configuration reference table 7 beingobtained by reading the input/output configuration definition table 5and transforming the table 5 into the format allowing the reference byeach computer for the execution of data input/output of eachinput/output device.

As shown in FIG. 1B, the input/output configuration definition table 5and input/output configuration reference table 7 each have the structureindicated at 8 in FIG. 1B.

Specifically, stored in a matrix form are the input/output deviceinformation part 9 for storing the data defining the identificationinformation 11 such as a type and an attribute of each input/outputdevice and the input/output device connection information part 10 forstoring the data defining the connection information between eachinput/output device and each computer. By referring to both the parts 9and 10, addition/deletion 13 of input/output devices andaddition/deletion 14 of computers are performed.

The identification information 11 is the definition information of theinput/output device entered upon system generation, such as anattribute, a name, and an address of each input/output device necessaryfor the execution of data input/output of the input/output device.

The input/output device configuration reference table 7 also stores datanecessary for the management of each input/output device by eachcomputer, such as whether what input/output device is in use by whatcomputer and whether what input/output device is inhibited to use.

The configuration management program 2 may run on all computers of themulti-computer system or on one or more computers of the multi-computer,system. As shown in FIG. 2, this configuration management program 2contains a system generation procedure 15 and a system alterationprocedure 16. The system generation procedure 15 generates theinput/output configuration definition table 5 and the changed data file6. In accordance with the changed data file 6, the system alterationprocedure 16 enters the information on addition, deletion, or change ofan input/output device and a computer into the input/outputconfiguration reference table 7 for the dynamic alteration of themulti-computer system. The changed data file 6 also stores a dynamicalteration flag. This flag is referred to by the system alterationprocedure 16 of the configuration management program 2 when the dynamicalteration is executed.

As shown in FIG. 3, the system generation procedure 15 of theconfiguration management program 2 includes an input/output deviceinformation generating process 15 a, an input/output device connectioninformation generating process 15 b, an input/output deviceconfiguration definition table diagnosing process, a changed data filegenerating process 15 d, and an input/output device configurationdefinition table copying process 15 e.

The input/output information generating process 15 a generates theinput/output device information part 9 and identification information 11of the configuration definition table 5.

The connection information generating process 15 b generates theinput/output device connection information part 10 and connectioninformation 12 of the configuration definition table 5.

The configuration definition table diagnosing process 15 c diagnoseswhether there is any data error or an integrity error between computersin the input/output device information part 9 and input/output deviceconnection information part 10 of the configuration definition table 5.

The changed data file generating process 15 d generates the changed datafile 6 which stores the changed data of the configuration definitiontable 5.

The configuration definition table copying process 15 e copies the datain the configuration definition table 5 to the configuration definitionworking table 5 a, or vice versa.

The connection information 12 is the information of a data route from aninput/output device of the subject computer to the subject input/outputdevice via a network channel.

As described above, the system generation procedure 15 therefore updatesthe input/output device configuration definition table 5.

As shown in FIG. 4, the system alteration procedure 16 of theconfiguration management program 2 includes an associative input/outputdevice identifying process 16 a, a dynamic system alteration startnotifying process 16 b, an input/output device use permission setting,process 16 c, an input/output device information part changing process16 d, an input/output device connection information part changingprocess 16 e, and a dynamic system alteration end notifying process 16f.

The associative input/output device identifying process 16 a identifiesany associative input/output device to be affected by the dynamic systemalteration, by using the changed data file 6.

The dynamic system alteration start notifying process 16 b notifies thestart of dynamic alteration of the configuration definition table 7 toall computers of the multi-computer system.

The use permission setting process 16 c sets a use permission of anassociative input/output device at the timing synchronously with allcomputers of the multi-computer system.

The input/output device information part changing process 16 d changesthe input/output device information part 9 of the configurationreference table 7 in accordance with the changed data file 6.

The input/output device connection information part changing process, 16e changes the input/output device information connection part 10 of theconfiguration reference table 7 in accordance with the changed data file6.

The dynamic system alteration end notifying process 16 f notifies theend of dynamic alteration of the configuration definition table 7 andthe changed data to all computers of the multi-computer system.

As described above, the system alteration procedure 15 therefore updatesthe input/output device configuration reference table 7.

Next, the system generation procedure 15 of the configuration managementprogram 2 of this embodiment constructed as above will be described withreference to the flow chart shown in FIG. 5.

First, the configuration definition table copying process 15 e copiesthe configuration definition table 5 to the configuration definitionworking table 5 a. The input/output information part generating process15 a checks whether there is any input/output device to be added,deleted, or changed. If there is such an input/output device, necessarydata is added to, deleted from, or changed in, the input/output deviceinformation part of the configuration definition working table 5 a. Inthis case, if there is an input/output device to be added, theidentification information 11 of the input/output device is defined.(Steps 101 to 103).

After the contents of the configuration definition working table 5 ahave been changed in accordance with the input/output device to beadded, deleted, or changed at Steps 102 and 103, the input/output deviceconnection information generating process 15 b checks whether there isany computer to be added, deleted, or changed. If there is such acomputer, necessary data is added to, deleted from, or changed in, theinput/output device connection information part 10 of the configurationdefinition working table 5 a. (Steps 104 and 105).

After the contents of the configuration definition working table 5 ahave been changed in accordance with the computer to be added, deleted,or changed at Steps 104 and 105, the input/output device connectioninformation part generating process 19 b changes for each input/outputdevice the connection information 12 of each computer in theinput/output device connection information part 10 of the configurationdefinition working table 5 a (Step 106).

After the contents of the configuration definition table 5 a have beenchanged, the configuration definition table diagnosing process 15 cchecks 10 whether there is any definition error or an integrity errorbetween computers in the changed configuration definition working table5 a. If there is an error, the procedure returns back to Step 102 tocorrect the configuration definition working table 5 a. (Steps 107 and108).

If the configuration definition working table 5 a is judged to becorrect at Step 108, it is checked whether a dynamic system alterationis performed. If a dynamic system alteration is to be performed, thechanged data file generating process 15 d generates the changed datafile 6. (Steps 109 and 110).

Thereafter, it is checked whether the dynamic system alteration istemporary. If temporary, the procedure is terminated without updatingthe configuration definition table 5 (Step 111).

If it is judged at Step 109 not to perform a dynamic system alterationat Step 109 or if it is judged at Step 111 not temporary, theconfiguration definition copying process 15 e overwrites theconfiguration definition working table 5 a to the configurationdefinition table 5 to update the latter (Step 112).

Next, the input/output device information part generating process 15 aof the system generation procedure 15 of the configuration managementprogram 2 will be described with reference to the flow chart shown inFIG. 8.

It is checked whether there is a system alteration and whether theconfiguration definition table 5 a is changed (Step 301).

In the case of a computer alteration, addition/deletion 14 (FIG. 1B) ofa computer is performed (Steps 302 and 303).

In the case of an input/output device alteration, addition/deletion 13of an input/output device is performed. In the case of an input/outputdevice addition, the identification information 11 is generated. (Steps304, 305, 306)

The input/output device connection information part generating process15 b of the system generation procedure 15 of the configurationmanagement program 2 will be described with reference to the flow chartshown in FIG. 9.

It is checked whether there is a system alteration and whether theconfiguration definition table 5 a is changed (Step 401).

Necessary data is added to, or deleted from, the connection information12 (Step 402).

The input/output device configuration definition table diagnosingprocessing of the system generation procedure 15 of the configurationmanagement program 2 will be described with reference to the flow chartshown in FIG. 10.

It is checked whether all computers have been diagnosed (Step 501).

The input/output connection information part of the next computer isdiagnosed (Step 502).

The changed data file generating process 15 d of the system generationprocedure 15 of the configuration management program 2 will be describedwith reference to the flew chart shown in FIG. 11.

It is checked whether all input/output devices in the configurationdefinition table 5 and in the configuration definition working table 5 ahave been searched (Step 601).

A difference of contents between the configuration definition table 5and configuration definition working table 5 a is Stored in the changeddata file 6 (Steps 602 and 603).

The input/output device configuration definition table copying process15 e of the system generation procedure 15 of the configurationmanagement program 2 will be described with reference to the flow chartshown in FIG. 12.

In the case of system generation start, the input/output deviceconfiguration definition table 5 is copied to the configurationdefinition working table 5 a (Steps 701 and 702).

In the case of system generation end, the configuration definitionworking table 5 a is copied to the input/output device configurationdefinition table 5 (Steps 701 and 103).

Next, the system alteration procedure 16 of the configuration managementprogram 2 will be described with reference to the flow chart shown inFIG. 6.

First, the associative input/output identifying process 16 a identifiesan input/output device considered to be affected by a dynamic systemalteration, in accordance with the changed data file 6. The dynamicsystem alteration start notifying process 16 b notifies a dynamic systemalteration start to all, computers so as to prevent two or morecomputers in the multi-computer system from executing the dynamic systemalteration at the same time. This notice may be performed, for example,by setting an indicator to the shared memory, by performingcommunications between computers, or by locking the shared file. (Steps201 and 202).

Next, the input/output device use permission setting process 16 cprohibits the associative input/output units from being used (Step 203).

Necessary data is added to, deleted from, or changed in the input/outputdevice information part 9 of the input/output configuration referencetable 7 for the associative input/output devices, by the input/outputdevice information part changing process 16 d (Steps 204 and 205).

After addition, deletion, or change of the input/output deviceinformation part 9 has been completed at Steps 204 and 205, necessarydata is added to, deleted from, or changed in the input/output deviceconnection information part 9 of the input/output configurationreference table 7 for the associative input/output devices, by theinput/output device connection information part changing process 16 e(Steps 207 and 208).

After addition, deletion, or change of the input/output deviceconfiguration reference table 7 has been completed at Steps 204 to 207,the input/output device use permission setting process 16 c permits theassociative input/output devices including an added input/output deviceto be used. Lastly, the dynamic system alteration end notifying process16 f notifies the end of a dynamic system alteration to all computers.(Steps 208 and 209)

After one computer 1 executes a dynamic system alteration and othercomputers 1 receive the notice of the end of a dynamic system alterationby the dynamic system alteration end notifying process 16 f, the othercomputers can refer to the altered configuration reference table 7without being explicitly given the changed contents.

The associative input/output device identifying process 16 a of thesystem alteration procedure 16 of the configuration management program 2will be described with reference to the flow chart shown in FIG. 13. Itis checked whether associative input/output devices of all computers 1have been identified (Step 801).

An associative input/output device of the next computer 1 is identified(Step 802).

The dynamic system alteration start notifying process 16 b of the systemalteration procedure 16 of the configuration management program 2 willbe described with reference to the flow chart shown in FIG. 14.

It is checked whether the start of a dynamic system alteration has beennotified to all computers (Step 901).

The start of a dynamic system alteration is notified to the nextcomputer (Step 902).

The input/output device use permission setting process 16 c of thesystem alteration procedure 16 of the configuration management program 2will be described with reference to the flow chart shown in FIG. 15.

It is checked whether use of associative input/output devices of allcomputers has been prohibited (Step 1001).

Use of associative input/output devices of the next computer isprohibited (Step 1002).

The input/output device information part changing process 16 d of thesystem alteration procedure 16 of the configuration management program 2will be described with reference to the flow chart shown in FIG. 16.

It is checked whether alteration of the input/output deviceconfiguration reference table 7 has been completed (Step 1101).

In the case of computer alteration, addition/deletion 14 (FIG. 1B) of acomputer is performed (Steps 1102 and 1103).

In the case of input/output device alteration, addition/deletion 13 ofan input/output device is performed, and the identification information11 is generated (Steps 1104 to 1106).

The, input/output device connection information part changing process 16e of the system alteration procedure 16 of the configuration managementprogram 2 will be described with reference to the flow chart shown inFIG. 17.

It is checked whether alteration of the input/output deviceconfiguration reference table 7 has been completed (Step 1201).

The connection information 12 is altered (Step 1202).

The dynamic system alteration end notifying process 16 f of the systemalteration procedure 16 of the configuration management program 2 willbe described with reference to the flow chart shown in FIG. 18. It ischecked whether the end of a dynamic system alteration has been notifiedto all computers (Step 1301).

The end of a dynamic system alteration is notified to the next computer(Step 1302). Next, the procedure of a dynamic system alteration will bedescribed with reference to FIGS. 1, 2, 4, and 7.

For the preparation of the dynamic system alteration, the systemgeneration procedure 15 of the configuration management program 2 runson one of computers 1 to generate the changed data file 6 which may begenerated at any time before the dynamic system alteration.

The dynamic system alteration is executed by the system alternationprocedure of the configuration management program 2 running on one ofcomputers 1.

The input/output device configuration reference table 7 has the status(a) depicted in FIG. 7 before the dynamic system alteration. In thiscase, all computers 1 can use possible associative input/output devicesas indicated at 7 a.

After the input/output device use permission process 16 c is executed,the input/output configuration reference table 7 has the status (b)depicted in FIG. 7. In this case, all computers 1 cannot use theassociative input/output devices as indicated at 7 b.

While the input/output device information part changing process 16 d andthe input/output device connection information, part changing process 16e are executed to change the contents of the input/output deviceconfiguration table 7 in accordance with the changed data file, thetable 7 has the status (c) depicted in FIG. 7. Also in this case, allcomputers 1 cannot use the associative input/output devices as indicatedat 7 c.

After the dynamic system alteration end notifying process 16 f isexecuted to notify the end of a dynamic system alteration, theinput/output configuration reference table 7 has the status (d) depictedin FIG. 7. In this case, all computers 1 are allowed to use theassociative input/output devices as indicated at 7 b, by referring tothe changed input/output configuration reference table 7.

After the completion of the dynamic system alteration, an addedinput/output device or an added computer is permitted to use.

According to the embodiment of the invention, in a multi-computer systemhaving a plurality of computers, any computer can define theconfiguration of input/output devices irrespective of whether they areshared or not. A shared input/output device is not required to bedefined by all computers. Accordingly, system generation is establishedonly by a single system generation operation so that the efficiency ofsystem generation can be improved.

Further, according to the embodiment of the invention, when a computeris booted up, the input/output device configuration definition table isread from the shared file and transformed into the input/outputconfiguration reference table having the format allowing the referenceby each computer for the execution of data input/output of eachinput/output device. The input/output configuration reference table isthen stored in the shared memory. Accordingly, the other computersbooted up thereafter are not required to read the input/outputconfiguration definition table, so that the computer boot-up time can beshortened.

Furthermore, according to the embodiment of the invention, theinput/output configuration definition table and the input/outputconfiguration reference table each have the input/output deviceinformation part and the input/output device connectioninformation-part-arranged in a matrix form. Accordingly, addition,deletion, or change of an input/output device and a computer can beeasily performed without any constrain so that the flexibility of systemconfiguration can be improved.

As described so far, according to the present invention, it is possibleto collectively manage the input/output device configuration definitiontable for storing the data defining the configurations of allinput/output devices used by a multi-computer system and theinput/output device configuration reference table transformed into theformat allowing the reference by each computer for the execution of datainput/output of each input/output device. Accordingly, the input/outputdevice configuration definition table and the input/output deviceconfiguration reference table can be dynamically updated when there is aneed of alteration of input/output devices and computers of themulti-computer system.

The invention can therefore improve the system generation efficiency,shorten a system boot-up time, and improve the system configurationflexibility.

1. An information processing system comprising: a plurality of computers; a plurality of storage devices coupled with and shared by said computers; a file which stores configuration information for said storage devices and different information having update information to update said configuration information; and a memory which stores configuration reference information used by said computers, wherein said configuration reference information is updated by using said configuration information and said different information.
 2. An information processing system comprising: a plurality of computers; a plurality of storage devices coupled with and shared by said computers; a shared file which stores configuration information for said storage devices and different information having update information to update said configuration information; and a shared memory which stores configuration reference information accessed by said computers, wherein said configuration reference information is updated by using said configuration information and said different information when a program of at least one of said computers is executed.
 3. An information processing system comprising: a plurality of computers; and a plurality of storage devices coupled with and shared by said computers, wherein one of said storage devices has stored therein configuration information for said storage devices and different information having update information to update said configuration information, and configuration reference information used by said computers, and wherein said configuration reference information is updated by using said configuration information and said different information.
 4. An information processing system comprising: a plurality of computers; and a plurality of storage devices coupled with and shared by said computers, wherein one of said storage devices has stored therein configuration information for said storage devices and different information having update information to update said configuration information, and configuration reference information accessed by said computers, and wherein said configuration reference information is updated by using said configuration information and said different information when a program of at least one of said computers is executed.
 5. A method in an information processing system having a plurality of computers and a plurality of storage devices coupled with and shared by said computers, said method comprising the steps of: storing, in a shared file, configuration information for said storage devices and differential information having update information to update said configuration information; storing, in a shared memory, configuration reference information accessed by said computers; and updating said configuration reference information by using said configuration information and said differential information when a program of at least one of said computers is executed.
 6. A method in an information processing system having a plurality of computers and a plurality of storage devices coupled with and shared by said computers, said method comprising the steps of: storing, in one of said storage devices, configuration information for said storage devices and differential information having update information to update said configuration information; storing, in one of said storage devices, configuration reference information accessed by said computers; and updating said configuration reference information by using said configuration information and said differential information when a program of at least one of said computers is executed. 